Multi-stage process and apparatus for recovering dichlorohydrins

ABSTRACT

A process and apparatus for recovering dichlorohydrins from a mixture comprising dichlorohydrins, one or more compounds selected from esters of dichlorohydrins, monochlorohydrins and/or esters thereof, and multihydroxylated-aliphatic hydrocarbon compounds and/or esters thereof, and optionally one or more substances comprising water, chlorinating agents, catalysts and/or esters of catalysts is disclosed. The mixture is distilled or fractionated to separate a lower boiling fraction comprising dichlorohydrin(s) from the mixture to form a higher boiling fraction comprising the residue of the distillation or fractionation. The higher boiling fraction is stripped to recover remaining dichlorohydrins. Advantages include more efficient recovery of dichlorohydrins for a given distillation column, less waste due to avoiding the conditions conducive to the formation of heavy byproducts, and reduced capital investment in recovery equipment.

BACKGROUND OF THE INVENTION

The present invention relates to processes and apparatus for recoveringdichlorohydrins from a mixture comprising the same such as the effluentgenerated by a process for converting multihydroxylated-aliphatichydrocarbon compound(s) and/or ester(s) thereof to chlorohydrins.

Dichlorohydrins are useful in preparing epoxides such asepichlorohydrins. Epichlorohydrin is a widely used precursor to epoxyresins. Epichlorohydrin is a monomer which is commonly used for thealkylation of para-bisphenol A. The resultant diepoxide, either as afree monomer or oligomeric diepoxide, may be advanced to high molecularweight resins which are used for example in electrical laminates, cancoatings, automotive topcoats and clearcoats.

Glycerin is considered to be a low-cost, renewable feedstock that is aco-product of the biodiesel process for making fuel. It is known thatother renewable feedstocks such as fructose, glucose and sorbitol can behydrogenolized to produce mixtures of vicinal diols and triols, such asglycerin, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycoland the like. With abundant and low cost glycerin or mixed glycols,economically attractive processes for recovering dichlorohydrins fromeffluents produced by the above processes are desired.

A process is known for the conversion of glycerol (also referred toherein as “glycerin”) to mixtures of dichloropropanols, compounds I andII, as shown in Scheme 1 below. The reaction is carried out in thepresence of anhydrous HCl and an acetic acid (HOAc) catalyst with waterremoval. Compounds I and II can then be converted to epichlorohydrin viatreatment with caustic or lime.

Various processes using the above chemistry in Scheme 1 have beenreported in the prior art. For example, epichlorohydrin can be preparedby reacting a dichloropropanol such as 2,3-dichloro-1-propanol or1,3-dichloro-2-propanol with base. Dichloropropanol, in turn, can beprepared at atmospheric pressure from glycerol, anhydrous hydrochloricacid, and an acid catalyst. A large excess of hydrogen chloride (HCl)was recommended to promote the azeotropic removal of water that isformed during the course of the reaction.

WO 2006/020234 A1 describes a process for conversion of a glycerol or anester or a mixture thereof to a chlorohydrin, comprising the step ofcontacting a multihydroxylated-aliphatic hydrocarbon compound, an esterof a multihydroxylated-aliphatic hydrocarbon, or a mixture thereof witha source of a superatmospheric partial pressure of hydrogen chloride toproduce chlorohydrins, esters of chlorohydrins, or mixtures thereof inthe presence of an organic acid catalyst. This process is also referredto herein as a “dry process”. Azeotropic removal of water in a dryprocess via a large excess of hydrogen chloride is not required toobtain high chlorohydrins yield. Separation of the product stream fromthe reaction mixture may be carried out with a suitable separationvessel such as one or more distillation columns, flash vessels,extraction columns or adsorption columns. WO 2006/020234 A1 does notdescribe a specific distillation method or a method to minimizeformation of heavy byproducts.

WO 2005/021476 A1 describes a process using atmospheric partial pressureof hydrogen chloride, acetic acid as the catalyst, and a cascade ofloops, preferably three loops, each loop consisting of a reactor and adistillation column in which water of reaction, residual hydrogenchloride and dichloropropanol are removed from the reaction effluent.This process for distillation requiring a cascade ofreactor/distillation loops is very expensive as it requires severalreactors/columns in the process. WO 2005/021476 A1 also does notdescribe a specific distillation method or a method to minimizeformation of heavy byproducts. Furthermore, valuable acetic acid is lostwith the distillate, needing to add more acetic acid to make up for thecatalyst loss in distillation.

EP 1 752 435 A1 discloses another process for producing a chlorohydrinby reaction between a multihydroxylated aliphatic hydrocarbon and/or anester thereof and aqueous hydrogen chloride to produce chlorohydrins,esters of chlorohydrins, or mixtures thereof under atmospheric conditionin which a purge from the reactor bottom is fed to a stripper in whichpartial stripping of most of unreacted hydrogen chloride, the water fromthe aqueous hydrogen chloride reactant and water that is formed duringthe course of the reaction (also referred to herein as “water ofreaction”), from the reaction mixture is carried out and a distillationor stripping column is fed with the liquid phase from the stripper. Thegas phase from the stripper, which contains most of the unreactedhydrogen chloride, the excess water from the aqueous hydrogen chloridereactant and the reaction by-product water from the reaction mixture, isconducted to a distillation column fed by the vapor produced by thereactor or is recycled directly to the reactor. The main fraction ofdichloropropanol is collected from the top of the distillation orstripping column. The column residue is recycled to reactor. Thisprocess (also referred to herein as a “wet process”), not only addswater via the aqueous hydrogen chloride reactant into the process, butalso produces water of reaction in the process. The removal of largeexcess of water in the wet process via stripper is less energy efficientand unnecessary for the dry process. A better utilization of thestripper can be done in the recovery of dichloropropanol. EP 1 752 435A1 also does not describe specific distillation method to minimizeformation of heavy byproducts.

CN 101007751A describes another process that combines wet and dryprocesses with two reactor in series, in which tubular reactor is usedas the first reactor and foaming-tank reactor is used as the secondreactor. Aqueous hydrogen chloride, glycerin, carboxylic acid catalystare mixed and fed to the first reactor and gaseous hydrogen chloride isfed to the second reactor. Inert impurities are added to the gaseoushydrogen chloride feed in order to improve the efficiency of strippingwater from the reaction mixture in the foaming-tank reactor. Theazeotropic composition of generated water, dichloropropanol and hydrogenchloride and part of the catalyst are evaporated from the top offoaming-tank reactor. The liquid bottom product of the foaming-tankreactor enters to a rectifying tower for separation. Thedichloropropanol product is obtained from the rectifying towerdistillates and the tower bottom residue is recycled to the foaming-tankreactor. This process shows lower hydrogen chloride conversion than thatof the dry process, generates excess water where azeotropic removal ofwater is required, which implies larger process equipment than that ofthe dry process. CN 101007751A also does not describe a specificdistillation method to minimize formation of heavy byproducts.

Opportunities remain to further improve the recovery of dichlorohydrinsin a form that can be used in subsequent conversions, such as theconversion to epichlorohydrin.

SUMMARY OF THE INVENTION

One aspect of the present invention is a process for recoveringdichlorohydrin(s) from a mixture comprising dichlorohydrin(s), one ormore compounds selected from ester(s) of chlorohydrin(s),monochlorohydrin(s), and/or multihydroxylated-aliphatic hydrocarboncompound(s) and/or ester(s) thereof, and optionally one or moresubstances comprising water, chlorinating agent(s), catalyst(s),ester(s) of catalyst(s), and/or heavy byproduct(s), wherein the processcomprises:

-   -   (a) providing a mixture comprising dichlorohydrin(s), one or        more compounds selected from ester(s) of chlorohydrin(s),        monochlorohydrin(s), and/or multihydroxylated-aliphatic        hydrocarbon compound(s) and/or ester(s) thereof, and optionally        one or more substances comprising water, chlorinating agent(s),        catalyst(s), ester(s) of catalyst(s), and/or heavy byproduct(s);    -   (b) distilling or fractionating the mixture of step (a) in one        or more unit operations to separate a lower boiling fraction        comprising dichlorohydrin(s) and other lower boiling components        present in the mixture from the mixture of step (a) to form a        higher boiling fraction comprising the residue of the        distillation or fractionation;    -   (c) introducing a stripping agent into the higher boiling        fraction produced by step (b) for contact with the higher        boiling fraction and stripping dichlorohydrin(s) from the higher        boiling fraction into the stripping agent to produce a vapor        fraction comprising dichlorohydrin(s) and stripping agent;    -   (d) recovering at least some of the lower boiling fraction of        step (b) and the vapor fraction of step (c).

Another aspect of the present invention is a method for producingdichlorohydrin(s), wherein the mixture provided in step (a) is producedor derived from hydrochlorination of monochlorohydrin(s) and/or ester(s)thereof and/or multihydroxylated-aliphatic hydrocarbon compound(s)and/or ester(s) thereof.

Yet another aspect of the present invention is an apparatus suitable forproducing dichlorohydrin(s) from multihydroxylated-aliphatic hydrocarboncompound(s) and/or ester(s) thereof comprising:

-   -   (1) at least one reactor;    -   (2) at least one separation device comprising at least one first        liquid-vapor contacting device having a bottom end and a top end        for applying a decreasing temperature gradient from the bottom        end to the top end to substances within the first liquid-vapor        contacting device; and    -   (3) at least one second contacting device for contacting a        liquid with a vapor-phase stripping agent,        wherein        the at least one reactor (1) is connected directly or indirectly        to the at least one separation device (2) for conducting a        reactor effluent feed stream (4) from the at least one reactor        (1) to the at least one first liquid-vapor contacting device of        the at least one separation device (2) for distillation and/or        fractionation,        the at least one separation device (2) is connected directly or        indirectly to the at least one second liquid-vapor contacting        device (3) for conducting a distilled or fractionated liquid        residue feed stream (5) from the at least one first liquid-vapor        contacting device of the at least one separation device (2) to        the at least one second liquid-vapor contacting device (3) for        stripping, the at least one separation device (2) having a first        port (6) for recovering a dichlorohydrin(s)-containing        distillate, and        the at least one second liquid-vapor contacting device (3) is        connected directly or indirectly to at least one source of        stripping agent (7) for introducing one or more stripping agents        into a distilled or fractionated liquid residue delivered to the        second liquid-vapor contacting device (3) via liquid residue        feed stream (5), the at least one second liquid-vapor contacting        device (3) having at least one second port (8) for recovering a        dichlorohydrin(s)-containing product stripped from a distilled        or fractionated liquid residue delivered to the second        liquid-vapor contacting device (3) via liquid residue feed        stream (5).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a process diagram illustrating one embodiment of the processof the present invention.

DETAILED DESCRIPTION OF THE INVENTION Definitions

As used herein, the term “multihydroxylated-aliphatic hydrocarboncompound” (abbreviated hereafter as “MAHC”) refers to a compound thatcontains at least two hydroxyl groups covalently bonded to two separatevicinal carbon atoms and no ether linking groups. They contain at leasttwo sp3 hybridized carbons each bearing an OH group. The MAHCs includeany vicinal-diol (1,2-diol) or triol (1,2,3-triol) containinghydrocarbon including higher orders of contiguous or vicinal repeatunits. The definition of MAHC also includes for example one or more1,3-1,4-, 1,5- and 1,6-diol functional groups as well. Geminal-diols,for example, are precluded from this class of MAHCs.

The MAHCs contain at least 2, preferably at least 3, up to about 60,preferably up to 20, more preferably up to 10, even more preferably upto 4, and yet more preferably up to 3, carbon atoms and can contain, inaddition to aliphatic hydrocarbon, aromatic moieties or heteroatomsincluding for example halide, sulfur, phosphorus, nitrogen, oxygen,silicon, and boron heteroatoms; and mixtures thereof. The MAHCs may alsobe a polymer such as polyvinyl alcohol.

The terms “glycerin”, “glycerol” and “glycerine”, and esters thereof,may be used as synonyms for the compound 1,2,3-trihydroxypropane, andesters thereof.

As used herein, the term “chlorohydrin” means a compound containing atleast one hydroxyl group and at least one chlorine atom covalentlybonded to two separate vicinal aliphatic carbon atoms and no etherlinking groups. Chlorohydrins are obtainable by replacing one or morehydroxyl groups of MAHCs with covalently bonded chlorine atoms viahydrochlorination. The chlorohydrins contain at least 2, and preferablyat least 3, up to about 60, preferably up to 20, more preferably up to10, even more preferably up to 4, and yet more preferably up to 3,carbon atoms and, in addition to aliphatic hydrocarbon, can containaromatic moieties or heteroatoms including for example halide, sulfur,phosphorus, nitrogen, oxygen, silicon, and boron heteroatoms, andmixtures thereof. A chlorohydrin that contains at least two hydroxylgroups is also a MAHC.

As used herein, the term “monochlorohydrin” means chlorohydrin havingone chlorine atom and at least two hydroxyl groups, wherein the chlorineatom and at least one hydroxyl group are covalently bonded to twoseparate vicinal aliphatic carbon atoms (referred to hereafter by theabbreviation “MCH”). MCH produced by hydrochlorination of glycerin orglycerin esters includes, for example, 3-chloro-1,2-propanediol and2-chloro-1,3-propanediol.

As used herein, the term “dichlorohydrin” means chlorohydrin having twochlorine atoms and at least one hydroxyl group, wherein at least onechlorine atom and at least one hydroxyl group are covalently bonded totwo separate vicinal aliphatic carbon atoms (referred to hereafter bythe abbreviation “DCH”). Dichlorohydrins produced by hydrochlorinationof glycerin or glycerin esters include 1,3-dichloro-2-propanol and2,3-dichloro-1-propanol.

As used herein, the expression “under hydrochlorination conditions”means conditions capable of converting at least 1 wt. %, preferably atleast 5 wt. %, more preferably at least 10 wt. % of MAHCs, MCHs, andesters of MAHCs and MCHs present in a mixture and/or feed stream intoDCH(s) and/or ester(s) thereof.

As used herein, the term “byproduct(s)” means compound(s) that is/arenot chlorohydrin(s) and/or ester(s) thereof and/or chlorinating agent(s)and that do not form chlorohydrin(s) and/or ester(s) thereof under thehydrochlorinating conditions selected according to the presentinvention.

The expression “heavy byproduct(s)” refer to oligomers of mixture (a)components, such as oligomers of MAHCs and/or esters thereof andoligomers of chlorohydrins and/or esters thereof, and derivatives ofsuch oligomers, such as esters thereof, chlorinated oligomers, and/orchlorinated esters thereof, having a number average molecular weightequal to or greater than the number average molecular weight of theoligomer, such as chlorinated oligomers. The terms chlorohydrin(s),MCH(s) and DCH(s), and ester(s) thereof, are not intended to includeheavy byproducts.

The term “epoxide” means a compound containing at least one oxygenbridge on a carbon-carbon bond. Generally, the carbon atoms of thecarbon-carbon bond are contiguous and the compound can include otheratoms than carbon and oxygen atoms, like hydrogen and halogens, forexample. Preferred epoxides are ethylene oxide, propylene oxide,glycidol and epichlorohydrin.

As used herein, the expression, “liquid phase” refers to a continuousintermediate phase between gas phase and a solid phase that mayoptionally comprise a minor amount of gas and/or solid discretephase(s). The liquid phase may comprise one or more immiscible liquidphases and may contain one or more dissolved solids, such as one or moreacids, bases, or salts.

As used herein, the expression “vapor phase” refers to a continuousgaseous phase that may optionally comprise a minor amount of liquidand/or solid discrete phase(s) (e.g., aerosol). The vapor phase may be asingle gas or a mixture, such as a mixture of two or more gases, two ormore liquid discrete phases, and/or two or more solid discrete phases.

The expression “lower boiling fraction” refers to a fraction derivedfrom the mixture provided in step (a) in which more than half the totalquantity of components of the lower boiling fraction are components ofthe mixture, or derived from the mixture, that are more volatile underthe conditions of the unit operation than the components of the higherboiling fraction in the same unit operation derived from the samemixture provided in step (a).

The expression “higher boiling fraction” refers to a fraction derivedfrom the mixture provided in step (a) in which more than half the totalquantity of components of the higher boiling fraction are components ofthe mixture, or derived from the mixture, that are less volatile thanthe components of the lower boiling fraction in the same unit operationderived from the same mixture provided in step (a).

As used herein, the expression “liquid-vapor contacting device” refersto devices that serve to provide the contacting and development of atleast one interfacial surface between liquid and vapor in the device.Examples of liquid-vapor contacting devices include plate column, packedcolumn, wetted-wall (falling film) column, spray chamber, heat exchangeror any combination thereof. Examples of devices comprising plate columnsand packed columns include distillation columns, fractionation columns,and stripping columns.

As used herein, the term “condenser” means a non-adiabatic system forremoving heat from a process fluid via a secondary fluid physicallyseparated from the process fluid. The process fluid and the secondaryfluid may each be a vapor, a liquid, or a combination of liquid andvapor. A condenser is generally associated with a section of adistillation or fractionation column. It may be a unit operationexternal to a distillation column or it may be a unit operation internalto a distillation column. The physical separation may be in the form oftubes and the condensation may be carried out on the inside or outsideof the tubes. The condenser may take the form of cooling elements on thedecks of distillation column fractionating trays or as cooling elementsbetween distillation column packing beds.

Mixture (a):

Mixture (a) may be obtained directly or indirectly from anyhydrochlorination process well-known in the art. For example, GermanPatent No. 197308 teaches a process for preparing a chlorohydrin by thecatalytic hydrochlorination of glycerin by means of anhydrous hydrogenchloride. WO 2005/021476 discloses a continuous process for preparingthe dichloropropanols by hydrochlorination of glycerin and/ormonochloropropanediols with gaseous hydrogen chloride with catalysis ofa carboxylic acid. WO 2006/020234 A1 describes a process for conversionof a glycerol or an ester or a mixture thereof to a chlorohydrin,comprising the step of contacting a MAHC, an ester of a MAHC, or amixture thereof with a source of a superatmospheric partial pressure ofhydrogen chloride to produce a chlorohydrin, an ester of a chlorohydrin,or a mixture thereof in the presence of an organic acid catalyst withoutsubstantially removing water. The above references are herebyincorporated herein by reference with respect to the above-describeddisclosures.

In an exemplifying hydrochlorination process, MAHC and ahydrochlorination catalyst are charged to the hydrochlorination reactor.Then a chlorinating agent such as hydrogen chloride is added to thereactor. The reactor pressure is adjusted to the desired pressure andthe reactor contents are heated to the desired temperature for thedesired length of time. After completion of the hydrochlorinationreaction or while carrying out the hydrochlorination reaction, thereactor contents as a reaction effluent stream is discharged from thereactor and fed directly, or indirectly via another reactor or otherintervening step, to a separation system comprising a DCH recoverysystem according to the present invention and optionally including otherseparation systems or equipment, such as a flash vessel and/or reboiler.

The hydrochlorination reaction above may be carried out in one or morehydrochlorination reactor vessels such as a single or multiplecontinuous stirred tank reactors (referred to hereafter by theabbreviation “CSTR”), single or multiple tubular reactor(s), plug flowreactors (referred to hereafter by the abbreviation “PFR”), orcombinations thereof. The hydrochlorination reactor can be, for example,one reactor or multiple reactors connected with each other in series orin parallel including, for example, one or more CSTRs, one or moretubular reactors, one or more PFRs, one or more bubble column reactors,and combinations thereof.

In a preferred embodiment, part or all of the hydrochlorination effluentstream is a feed stream from a PFR. A PFR is a type of reactor that hasa high length/diameter (L/D) ratio and has a composition profile alongthe length of the reactor. The concentration of the reactants being fedinto the PFR decreases from inlet to the outlet along the flow path ofthe PFR and the concentration of DCHs increases from inlet to the outletalong the flow path of the PFR. In the case of hydrochlorination ofglycerol, the concentration of HCl and glycerol decreases from inlet ofthe PFR to outlet of the PFR while the total concentration of1,3-dichloro-2-propanol and 2,3-dichloro-1-propanol increases from inletof the PFR to the outlet of the PFR.

The equipment useful for conducting the hydrochlorination reaction maybe any well-known equipment in the art and should be capable ofcontaining the reaction mixture at the conditions of thehydrochlorination. Suitable equipment may be fabricated of materialswhich are resistant to corrosion by the process components, and mayinclude for example, metals such as tantalum, suitable metallic alloys(particularly nickel-molybdenum alloys such as Hastalloy C©), orglass-lined equipment, for example.

In addition to DCH(s), one or more of the unreacted MAHC(s) and/orchlorination agent(s), reaction intermediates such as MCH(s), MCHester(s), and/or DCH ester(s), catalyst(s), ester(s) of catalyst(s),water, and/or heavy byproduct(s) may present in mixture (a). A recycleprocess is preferred in which one or more of the unreacted MAHC(s),ester(s) of MAHC(s) and/or chlorination agent(s), reaction intermediatessuch as MCH(s), MCH ester(s), DCH ester(s), and other substances such ascatalyst(s), ester(s) of catalyst(s), and water are preferably recycledto a prior step in the process, such as to at least onehydrochlorination reactor for further hydrochlorination. In particular,a liquid higher boiling fraction comprising a residue of the strippingstep containing one or more of MAHC(s), MCH(s), catalyst(s), and/orester(s) of one or more MAHC(s), MCH(s), DCH(s) and/or catalyst(s), andpreferably a combination of two or more thereof, is recycled to thehydrochlorination step, such as by recycling the higher boiling fractionto one or more reactor(s), Such recycle process(es) is preferablycontinuous. In this manner, raw material efficiencies are maximizedand/or catalysts are reused.

When catalysts are reused in such a process scheme, it may be desirableto employ the catalysts in a higher concentration than they are employedin a single-pass process. This may result in faster reactions, orsmaller process equipment, which results in lower capital costs for theequipment employed.

In a continuous recycle process, undesirable impurities and/or reactionbyproducts may build up in the process. Thus, it is desirable to providea means for removing such impurities from the process, such as via oneor more purge outlets, for example, or by a separation step.Furthermore, a purged stream may be further treated to recover a usefulportion of the purged stream.

The chlorinating agent that may optionally be present in the mixturetreated according to the present invention is preferably hydrogenchloride or hydrogen chloride source, and may be a gas, a liquid or in asolution, or a mixture thereof. The hydrogen chloride is preferablyintroduced in the gaseous state and, when the hydrochlorination reactionmixture is in the liquid phase, at least some of the hydrogen chloridegas is preferably dissolved in the liquid reaction mixture. The hydrogenchloride may, however, be diluted in a solvent, such as an alcohol (forexample methanol) or a chlorinated hydrocarbon, or in a carrier gas suchas nitrogen, if desired.

It is preferred that the hydrochlorination step of the present inventionbe carried out under superatmospheric pressure conditions.“Superatmospheric pressure” herein means that the hydrogen chloride(HCl) partial pressure is above atmospheric pressure, i.e. 15 psia (103kPa) or greater. Generally, the hydrogen chloride partial pressureemployed in the hydrochlorination process is at least about 15 psia (103kPa) or greater. Preferably, the hydrogen chloride partial pressureemployed in the hydrochlorination process is not less than about 25 psia(172 kPa), more preferably not less than about 35 psia (241 kPa), andmost preferably not less than about 55 psia (379 kPa); and preferablynot greater than about 1000 psia (6.9 MPa), more preferably not greaterthan about 600 psia (4.1 MPa), and most preferably not greater thanabout 150 psia (1.0 MPa).

It is also preferred to conduct the hydrochlorination step at atemperature sufficient for hydrochlorination that is also below theboiling point of the chlorohydrin(s) in the reaction mixture having thelowest boiling point for a given pressure condition during thehydrochlorination step in order to keep the chlorohydrin(s) produced andconverted during hydrochlorination in the liquid phase of the reactionmixture for recovery in steps (b) and (c). The upper limit of thispreferred temperature range may be adjusted by adjusting the pressurecondition. A higher pressure during hydrochlorination may be selected toincrease the boiling point temperature of the chlorohydrin(s) in thereaction mixture, so that the preferred temperature range for keepingDCH(s) in the liquid phase may be increased by increasing the pressurecondition.

Preferably, less than 50, more preferably less than 10, even morepreferably less than 5, and yet more preferably less than 1, percent ofthe DCH present in the hydrochlorination effluent is removed from thehydrochlorination effluent prior to step (b).

The hydrochlorination effluent comprises one or more DCHs, one or morecompounds comprising ester(s) of DCH(s), MCH(s) and/or ester(s) thereof,and MAHC(s) and/or ester(s) thereof, and optionally one or moresubstances comprising water, chlorination agent(s), catalyst(s) and/orester(s) of catalyst(s). Additional optional components may also bepresent in the effluent depending on the starting materials, reactionconditions, and any process steps intervening between thehydrochlorination reaction and recovery of DCH according to the presentinvention. The hydrochlorination effluent is preferably in the liquidphase as the hydrochlorination effluent is withdrawn from thehydrochlorination step and/or reactor and the mixture provided in step(a) comprises at least part of the liquid phase effluent of thehydrochlorination step.

In a preferred embodiment, at least one MAHC and/or ester thereof ispresent in the mixture provided in step (a). When MAHC(s) and/orester(s) thereof is/are present in the mixture provided in step (a), thesame MAHC(s) and/or ester(s) thereof may also be present in thehigh-boiling fraction of step (b).

MAHCs found in the effluent treated according the present invention mayinclude for example 1,2-ethanediol; 1,2-propanediol; 1,3-propanediol;3-chloro-1,2-propanediol; 2-chloro-1,3-propanediol; 1,4-butanediol;1,5-pentanediol; cyclohexanediols; 1,2-butanediol;1,2-cyclohexanedimethanol; 1,2,3-propanetriol (also known as, and usedherein interchangeable as, “glycerin”, “glycerine”, or “glycerol”); andmixtures thereof. Preferably, the MAHCs in the effluents treatedaccording to the present invention include for example 1,2-ethanediol;1,2-propanediol; 1,3-propanediol; and 1,2,3-propanetriol; with1,2,3-propanetriol being most preferred.

Examples of esters of MAHCs found in the effluents treated according tothe present invention include for example ethylene glycol monoacetate,propanediol monoacetates, glycerin monoacetates, glycerin monostearates,glycerin diacetates, and mixtures thereof. In one embodiment, suchesters can be made from mixtures of MAHC with exhaustively esterifiedMAHC, for example mixtures of glycerol triacetate and glycerol.

In the same or another preferred embodiment, at least one MCH and/orester thereof is present in the mixture provided in step (a). WhenMCH(s) and/or ester(s) thereof is/are present in the mixture provided instep (a), the same MCH(s) and/or ester(s) thereof may also be present inthe high-boiling fraction of step (b).

The MCHs generally correspond to the hydrochlorinated MAHCs in which oneof a pair of hydroxyl groups covalently bonded to two separate vicinalcarbon atoms is replaced by a covalently bonded chlorine atom. Theester(s) of MCH may be the result of hydrochlorination of MAHC ester(s)or reaction with an acid catalyst, for example.

The DCHs generally correspond to the hydrochlorinated MAHCs in which twohydroxyl groups covalently bonded to two separate carbon atoms, at leastone of which is vicinal to a third carbon atom having a hydroxyl group,are each replaced by a covalently bonded chlorine atom. The ester(s) ofDCH may be the result of hydrochlorination of MAHC ester(s), MCHester(s) or reaction(s) with acid catalyst(s), for example.

In an embodiment of the present invention where MAHC(s) is/are thestarting material fed to the process, as opposed to ester(s) of MAHC(s)or a mixture of MAHC(s) and ester(s) thereof as a starting material, itis generally preferred that the formation of chlorohydrin be promoted bythe presence of one or more catalyst(s) and/or ester(s) thereof.Catalyst(s) and/or ester(s) thereof may also be present where ester(s)of MAHC(s), or a mixture of MAHC(s) and ester(s) thereof, is a startingmaterial to further accelerate the hydrochlorination reaction.

Carboxylic acids, RCOOH, catalyze the hydrochlorination of MAHCs tochlorohydrins. The specific carboxylic acid catalyst chosen may be basedupon a number of factors including for example, its efficacy as acatalyst, its cost, its stability to reaction conditions, and itsphysical properties. The particular process, and process scheme in whichthe catalyst is to be employed may also be a factor in selecting theparticular catalyst. The “R” groups of the carboxylic acid may beindependently chosen from hydrogen or hydrocarbyl groups, includingalkyl, aryl, aralkyl, and alkaryl. The hydrocarbyl groups may be linear,branched or cyclic, and may be substituted or un-substituted.Permissible substituents include any functional group that does notdetrimentally interfere with the performance of the catalyst, and mayinclude heteroatoms. Non-limiting examples of permissible functionalgroups include chloride, bromide, iodide, hydroxyl, phenol, ether,amide, primary amine, secondary amine, tertiary amine, quaternaryammonium, sulfonate, sulfonic acid, phosphonate, and phosphonic acid.

The carboxylic acids useful as hydrochlorination catalysts may bemonobasic such as acetic acid, formic acid, propionic acid, butyricacid, isobutyric acid, hexanoic acid, 4-methylvaleric acid, heptanoicacid, oleic acid, or stearic acid; or polybasic such as succinic acid,adipic acid, or terephthalic acid. Examples of aralkyl carboxylic acidsinclude phenylacetic acid and 4-aminophenylacetic acid. Examples ofsubstituted carboxylic acids include 4-aminobutyric acid,4-dimethylaminobutyric acid, 6-aminocaproic acid, 6-hydroxyhexanoicacid, 6-chlorohexanoic acid, 6-aminohexanoic acid, 4-aminophenylaceticacid, 4-hydroxyphenylacetic acid, lactic acid, glycolic acid,4-dimethylaminobutyric acid, and 4-trimethylammoniumbutyric acid.Additionally, materials that can be converted into carboxylic acidsunder reaction conditions, including for example carboxylic acidhalides, such as acetyl chloride, 6-chlorohexanoyl chloride,6-hydroxyhexanoyl chloride, 6-hydroxyhexanoic acid, and4-trimethylammonium butyric acid chloride; carboxylic acid anhydridessuch as acetic anhydride and maleic anhydride; carboxylic acid esterssuch as methyl acetate, methyl propionate, methyl pivalate, methylbutyrate, ethylene glycol monoacetate, ethylene glycol diacetate,propanediol monoacetates, propanediol diacetates, glycerin monoacetates,glycerin diacetates, glycerin triacetate, and glycerin esters of acarboxylic acid (including glycerin mono-, di-, and tri-esters); MAHCacetates such as glycerol 1,2-diacetate; carboxylic acid amides such asε-caprolactam and γ-butyrolactam; and carboxylic acid lactones such asγ-butyrolactone, δ-valerolactone and ε-caprolactone may also be employedin the present invention. Zinc acetate is an example of a metal organiccompound. Mixtures of the foregoing catalysts and catalyst precursorsmay also be used.

When a catalyst is used in the superatmospheric pressure process, thecatalyst may be for example a carboxylic acid; an anhydride; an acidchloride; an ester; a lactone; a lactam; an amide; a metal organiccompound such as sodium acetate; or a combination thereof. Any compoundthat is convertible to a carboxylic acid or a functionalized carboxylicacid under hydrochlorination reaction conditions may also be used. Apreferred carboxylic acid for the superatmospheric pressure process isan acid with a functional group consisting of a halogen, an amine, analcohol, an alkylated amine, a sulfhydryl, an aryl group or an alkylgroup, or combinations thereof, wherein this moiety does not stericallyhinder the carboxylic acid group.

Certain catalysts may also be advantageously employed atsuperatmospheric, atmospheric or sub-atmospheric pressure, andparticularly in circumstances where water is continuously orperiodically removed from the reaction mixture to drive conversion todesirably higher levels as may be the case when recovering DCH(s)according to the claimed invention. For example, the hydrochlorinationof MAHC(s) reaction can be practiced by introducing hydrogen chloridegas into contact with a mixture of MAHC(s) and catalyst(s), such as bysparging the hydrogen chloride gas through a liquid phase reactionmixture. In such a process, the use of less volatile catalysts, such as6-hydroxyhexanoic acid, 4-aminobutyric acid; dimethyl 4-aminobutyricacid; 6-chlorohexanoic acid; caprolactone; carboxylic acid amides suchas ε-caprolactam and γ-butyrolactam; carboxylic acid lactones such asγ-butyrolactone, δ-valerolactone and ε-caprolactone; caprolactam;4-hydroxyphenyl acetic acid; 6-amino-caproic acid; 4-aminophenylaceticacid; lactic acid; glycolic acid; 4-dimethylamino-butyric acid;4-trimethylammoniumbutyric acid; and combination thereof; and the likemay be preferred. It is most desirable to employ a catalyst, under theseatmospheric or subatmospheric conditions, that is less volatile than theDCH(s) produced and recovered.

Preferred catalysts used in the present invention include carboxylicacids, esters of carboxylic acids, and combinations thereof,particularly esters and acids having a boiling point higher than that ofthe desired highest boiling DCH that is formed in the reaction mixture(i.e., the catalyst(s) is/are preferably less volatile than the DCH(s)in the mixture), so that the DCH(s) can be removed without removing thecatalyst. Catalysts which meet this definition and are useful in thepresent invention include for example, polyacrylic acid, glycerin estersof carboxylic acids (including glycerin mono-, di-, and tri-esters),polyethylene grafted with acrylic acid, divinylbenzene/methacrylic acidcopolymer, 6-chlorohexanoic acid, 4-chlorobutanoic acid, caprolactone,heptanoic acid, 4-hydroxyphenylacetic acid, 4-aminophenylacetic acid,6-hydroxyhexanoic acid, 4-aminobutyric acid, 4-dimethylaminobutyricacid, 4-trimethyl-ammoniumbutyric acid chloride, stearic acid,5-chlorovaleric acid, 6-hydroxyhexanoic acid, 4-aminophenylacetic acid,and mixtures thereof. Carboxylic acids that are sterically unencumberedaround the carboxylic acid group are generally preferred.

Furthermore, the catalyst(s) is/are preferably miscible with the MAHC(s)employed. For this reason, the catalyst(s) may contain polar heteroatomsubstituents such as hydroxyl, amino or substituted amino, or halidegroups, which render the catalyst miscible with the MAHC(s) in thereaction mixture, such as glycerol.

One embodiment of the catalyst that may be present is generallyrepresented by Formula (a) shown below wherein the functional group “R′”includes a functional group comprising an amine, an alcohol, a halogen,a sulfhydryl, an ether; or an alkyl, an aryl or alkaryl group of from 1to about 20 carbon atoms containing said functional group; or acombination thereof; and wherein the functional group “R” may include ahydrogen, an alkali, an alkali earth or a transition metal or ahydrocarbon functional group.

Where the catalyst is recycled and used repeatedly, such recycledcatalysts may be present in an amount from about 0.1 mole %, preferablyfrom about 1 mole %, more preferably from about 5 mole %, up to about99.9 mole %, preferably up to 70 mol %, and more preferably up to 50mole %, based on the amount in moles of MAHC present. Higher catalystsconcentrations may be desirably employed to reduce the reaction time andminimize the size of process equipment.

In a preferred embodiment, the mixture (a) comprises water, such as thewater produced as a byproduct of the hydrochlorination reaction, waterpresent in the starting materials for the hydrochlorination reaction,and/or water introduced as the stripping agent. The mixture (a) maycontain at least 1, more preferably at least 5, weight-percent water upto 90, more preferably up to 50, weight-percent water.

The mixture of step (a) may be a combination of liquid phase and vaporphase. The mixture of step (a) is preferably provided to the separationstep as a liquid phase as opposed to a gaseous or vapor phase.

In one embodiment, the mixture of step (a) is provided to step (b) byseparating a hydrochlorination reaction effluent stream into avapor-phase effluent stream and a liquid-phase effluent stream prior tostep (b) and introducing the liquid-phase effluent stream or both thevapor-phase effluent stream and the liquid-phase effluent stream,separately or combined, into step (b). The separation of the reactioneffluent stream may be carried out in, for example, a flash vesselseparate from or integral with step (b).

Recovery of DCH from the mixture (a):

Recovery of DCH according to the present invention takes place in twosteps. First, the mixture (a) is distilled and/or fractionated toseparate a lower boiling fraction comprising dichlorohydrin(s) from themixture of step (a) to form a higher boiling fraction comprising theresidue of the distillation or fractionation. DCH(s), and preferablywater, may be recovered from the lower boiling fraction of step (b).

Then the residue of the distillation and/or fractionation is stripped(c) by introducing at least one stripping agent into contact with thehigher boiling fraction produced by step (b) for strippingdichlorohydrin(s) from the higher boiling fraction with the at least onestripping agent to produce a vapor fraction enriched with DCH(s) and theat least one stripping agent. Stripping step (c) is preferably carriedout on the higher boiling fraction produced in step (b) after removingthe higher boiling fraction produced in step (b) from the distillationor fractionation step (b).

Since the distillation residue is stripped in stripping step (c), step(b) may be conducted under milder separation conditions than thoserequired to optimize DCH recovery. DCH(s), and preferably water, may berecovered from the lower boiling fraction of step (b). The temperatureand pressure for step (b) are preferably adjusted to recover at least 1,more preferably at least 10, even more preferably at least 25, and yetmore preferably at least 50, and up to 99, more preferably up to 95, yetmore preferably up to 90, yet even more preferably up to 80, and evenmore preferably up to 70, weight-percent of the total amount of DCH inthe mixture provided in step (a) via the lower boiling fraction producedin step (b).

Milder separation conditions may include reducing the temperature of thedistillation bottoms to reduce energy consumption and reduce the rate ofheavy byproduct formation during step (b). Safety and efficiency areimproved when the distillation column is operated at lower bottomtemperature.

Distillation or fractionation step (b) is preferably carried out at atemperature measured in the distillation bottoms of at least 25° C.,more preferably at least 50° C., yet more preferably at least 80° C.,even more preferably at least 100° C., and yet even more preferably atleast 110° C., up to 200° C., more preferably up to 160° C., yet morepreferably up to 140° C., even more preferably up to 139° C., yet evenmore preferably up to 135° C., yet even more preferably up to 132° C.,yet even more preferably up to 125° C., and yet even more preferably upto 120° C.

Milder separation conditions may also include operation of step (b)under pressure conditions higher than those used in conventionalprocesses for separating DCH(s) from reactor effluents. The higherpressure condition process allows for energy savings and a widerselection of vacuum devices. A more economical steam-jet ejector orvacuum pump can be used, which reduces fixed capital and operatingcosts. Operational reliability is also improved through the use ofsteam-jet ejectors, because steam-jet ejectors do not have moving parts,while low pressure, high vacuum operation generally requires the use ofrotary oil-sealed vacuum pumps or multiple stages of steam-jet ejectors.Also higher distillation column pressure operation reduces column size,thereby reducing the capital investment to be amortized.

The distillation or fractionation step (b) is preferably carried out ata pressure of at least 0.1 kPa, more preferably at least 1 kPa, evenmore preferably at least 3 kPa, yet more preferably at least 6 kPa, andeven more preferably at least 10 kPa, up to 1 MPa, more preferably up to0.12 MPa, yet more preferably up to 0.05 MPa, and even more preferablyup to 0.02 MPa.

The percent DCH(s) recovered from the mixture introduced into step (b)generally depends on the combination of temperature and pressureconditions selected. To obtain a given DCH recovery in step (b), areduction in temperature generally requires a reduction in operatingpressure and an increase in operating pressure, conversely, generallyrequires an increase in operating temperature. The specific temperatureand pressure conditions selected will depend on the extent to whichrealization of the respective benefits relating to low temperature andhigher pressure operation is desired.

Step (b) is preferably carried out under conditions such that the amountof heavy byproducts in the high boiling fraction of step (b) does notexceed 110 percent, more preferably not more than 108 percent, even morepreferably not more than 105 percent, and even more preferably not morethan 102 percent, of the amount of heavy byproducts in the mixtureprovided in step (a).

The conditions during step (b) are preferably adjusted to produce ahigher boiling fraction containing less than 50, more preferably lessthan 20, even more preferably less than 10, and yet even more preferablyless than 5, percent of the chlorinating agent(s) present in the mixtureprovided in step (a). One or more conditions of step (b), such as thetemperature and pressure, may be adjusted to remove chlorinatingagent(s) from the mixture (a) provided to step (b).

When the chlorinating agent is hydrogen chloride for example, thehydrogen chloride may be removed from the mixture (a) during step (b) bymaintaining a pressure during step (b) that is below the pressurerequired to maintain dissolution of the hydrogen chloride present in themixture provided in step (a) and/or maintaining a temperature duringstep (b) that is greater than the temperature required to maintaindissolution of the hydrogen chloride present in the mixture provided instep (a).

In a preferred embodiment, the mixture provided in step (a) is passedthrough a pressure letdown step for degassing the mixture prior todistilling and/or fractionating the mixture. When there are flowfluctuations or surges upstream from the distillation and/orfractionation step, the pressure letdown step and/or a surge vessel mayalso be used to help regulate the flow of the mixture into thedistillation and/or fractionation step.

Step (b) is preferably carried out in a distillation column, such as afractional distillation column. Examples of suitable distillationcolumns include a plate or tray columns, bubble cap columns and packedcolumns.

In one embodiment, additional MAHC(s) and/or ester(s) thereof may beintroduced into step (b) for reactive distillation/fractionation. Theadditional MAHC(s) and/or ester(s) thereof may react with thechlorination agent to produce additional MCH(s) and/or ester(s) thereof.Additional MAHC(s) may also react with ester(s) of DCH(s) and MCH(s) toconvert them to non-ester(s) to facilitate recovery of DCH(s). Theadditional MAHC(s) and/or ester(s) thereof is/are preferably introducedas a liquid phase into a reflux to provide additional liquid phase forreflux.

In a preferred embodiment, step (b) comprises:

-   -   (b1) vaporizing an azeotropic mixture of DCH(s) and water from        the mixture of step (a) to separate a lower boiling fraction        comprising at least DCH(s) and water from the mixture of        step (a) and    -   (b2) condensing the low boiling fraction of step (b1) to form a        liquid aqueous phase and a liquid organic phase comprising        DCH(s).

The condensing step (b2) may comprise refluxing in a distillationcolumn, such as a fractional distillation column and/or a packeddistillation column.

In one embodiment, additional MAHC(s) and/or ester(s) thereof may beintroduced into condensing step (b2) for reactivedistillation/fractionation for the reasons stated above. Such additionalso increases the amount of liquid available for reflux duringdistillation/fractionation, which increases the efficiency with whichstep (b) separates DCH and water from the other components of themixture (a) provided to step (b).

Step (b) may further comprise:

-   -   (b3) separating the liquid aqueous phase of step (b2) from the        liquid organic phase of step (b2) and    -   (b4) recycling at least some of the liquid aqueous phase of step        (b3) to step (b1) and/or step (b2).

Recycling the liquid aqueous phase to step (b1) may be used tofacilitate recovery of DCH by azeotroping and/or stripping DCH(s) fromthe reaction mixture.

Recycling the liquid aqueous phase to step (b2) may be used to provideadditional liquid for reflux during step (b). When sufficient liquidaqueous phase is recycled to step (b2), the liquid aqueous phase mayflow to the bottom of the distillation/fraction apparatus, so that atleast some of the same liquid aqueous phase is also recycled to step(b1) where it may also facilitate recovery of DCH by azeotroping and/orstripping DCH(s) from the reaction mixture.

In step (c), a stripping agent is introduced into the higher boilingfraction produced by step (b). Preferred stripping agents include steam,nitrogen, methane and carbon dioxide, and mixtures thereof.

The stripping agent is preferably an azeotroping agent for the DCH(s) inthe high boiling fraction produced in step (b). Such stripping agentsinclude steam. Superheated steam is more preferred.

The stripping agent is preferably introduced into the higher boilingfraction at a temperature equal to or greater than the temperature ofthe higher boiling fraction during step (b) and is preferably introducedat a temperature equal to or greater than the boiling point of the DCHand water azeotrope at the pressure condition of step (c). The strippingagent is preferably introduced into the higher boiling fraction at atemperature that is greater, such as at least 10° C., or 20° C., or 30°C. greater, than the temperature of the higher boiling fraction tocompensate for heat loss during step (c) and thereby maintain the highboiling fraction at the desired elevated temperature.

Step (c) is preferably carried out at a high boiling fractiontemperature of at least 25° C., more preferably at least 100° C., up to140° C., and more preferably up to 130° C. and at a pressure of at least14 kPa, preferably at least 21 kPa, up to 0.2 MPa, more preferably up to0.1 MPa, and even more preferably up to 50 kPa. For economic reasons,step (c) may be carried out at atmospheric pressure.

Step (c) may further comprise distilling or fractionating the vaporfraction of step (c) for isolating dichlorohydrin(s) and strippingagent.

One or more stripping agents may also be introduced into the higherboiling fraction of step (b) while the same higher boiling fraction isdistilled or fractionated according to step (b) for contact with thehigher boiling fraction undergoing distillation or fractionation andstripping DCH(s) from the higher boiling fraction. The above descriptionof preferred stripping agents and preferred conditions for introductioninto step (c) apply to the introduction of stripping agent(s) duringstep (b).

The lower boiling fraction produced by step (b) and the vapor fractionproduced in step (c) recovered in step (d) may be recovered separatelyand subjected to further processing steps or they may be combined.Depending on the further processing steps, the lower boiling fractionand/or the vapor fraction may be used separately or combined to supplyDCHs for chemical conversion into other compounds without furtherprocessing. The lower boiling fraction/vapor fraction mixture may beused in used in processes for conversion of DCH(s) into otherindustrially useful chemical products.

The lower boiling fraction and/or the vapor fraction recovered in step(d) may, for example, be subjected to epoxidation to formepichlorohydrin without additional purification of the dichlorohydrin(s)other than via the above-described optional liquid-liquid phaseseparation for recycling an aqueous phase in step (b3) or via theabove-described optional distillation or fractionation of the vaporfraction produced during step (c). An advantage of the present inventionis that the steam introduced in step (c) not only improves DCH recovery,but also provides water to the downstream epoxidation process forkeeping the concentration of sodium chloride formed during epoxidationat a concentration below saturation to avoid undesirable sodium chloridecrystallization during epoxidation.

Any combination of the above process steps may be carried outindependently or simultaneously with one another. In a preferredembodiment, one or more of the above process steps is carried outsimultaneously with one another.

One or more of the above process steps may be carried out continuouslyor discontinuously. One or more of the above process steps arepreferably carried out continuously (i.e., without interruption) for atime period of at least one hour. Preferably, all the above processsteps are carried out continuously for a time period of at least onehour.

At least some of the higher boiling fraction treated in step (c) ispreferably recycled to a hydrochlorination step. In a more preferredembodiment, substantially all the higher boiling fraction treated instep (c) is recycled to a hydrochlorination step. The hydrochlorinationstep is preferably the first step in the hydrochlorination process usedto produce a hydrochlorination effluent containing components of themixture (a).

Recycling the treated higher boiling fraction permits further reactionof MAHC(s) and/or ester(s) thereof and/or MCH(s) and/or ester(s) thereofto form additional DCH, which generally increases the overallhydrochlorination conversion and recovery rates. In that case, theprocess according to the present invention may recover at least 80percent, more preferably at least 90 percent, even more preferably atleast 95 percent, yet more preferably at least 99 percent, and yet evenmore preferably at least 99.9 percent of the DCH(s) produced duringhydrochlorination.

The above process may be conducted using an apparatus according to thepresent invention. The apparatus is now described in more detail inreference to FIG. 1.

FIG. 1 is a block diagram showing the main features of an illustrativeapparatus that may be used and their respective feed streams. Theapparatus comprises at least one reactor (1); at least one separationdevice (2) comprising at least one first liquid-vapor contacting devicehaving a bottom end and a top end for applying a gradually decreasingtemperature gradient from the bottom end to the top end to substanceswithin the column; and at least one second liquid-vapor contactingdevice (3) for contacting a liquid phase material with a strippingagent.

The at least one reactor (1) may be selected from various knownreactors, such as CSTRs, tubular reactors, and PFRs, and combinationsthereof. When multiple reactors are present, the reactors may beconnected to each other in series or parallel. At least one reactor (1)is connected directly or indirectly to a first feed stream (12)comprising MAHC(s) and a second feed stream (13) comprising chlorinatingagent.

The at least one reactor (1) is connected directly or indirectly to theat least one separation device (2) for conducting at least part of areactor effluent feed stream (4) from the at least one reactor (1) tothe at least one first liquid-vapor contacting device of separationdevice (2) for distillation and/or fractionation. The connection forconducting a reactor effluent feed stream (4) from the at least onereactor (1) is preferably adapted to conduct a liquid-phase feed streamfrom the at least one reactor (1).

The at least one separation device (2) comprises a first port (6) forrecovering an effluent stream comprising DCH(s) separated from thereactor effluent feed stream (4) via the at least one first liquid-vaporcontacting device of separation device (2) and preferably comprises afirst vent (14) for removing gases at the top of the at least one firstliquid-vapor contacting device of the separation device (2).

The at least one separation device (2) preferably comprises a means forapplying a vacuum to the at least one first liquid-vapor contactingdevice of the at least one separation device (2) for reducing thepressure in the at least one column (2) below ambient atmosphericpressure. The means is preferably a steam-jet ejector.

The at least one first liquid-vapor contacting device of the at leastone separation device (2) is preferably a distillation or fractionationcolumn, such as a packed distillation column and/or a distillationcolumn adapted for carrying out fractional distillation under refluxconditions having a reflux zone for carrying out reflux.

The at least one separation device (2) preferably comprises at least oneflash vessel and the at least one reactor (1) is connected to at leastone first liquid-vapor contacting device of the at least one separationdevice (2) via the at least one flash vessel, whereby the feed streamconducted from the reactor (1) is separated into a vapor phase and aliquid phase in the flash vessel by reducing the pressure on the liquidphase and the separated liquid phase is introduced into the firstliquid-vapor contacting device of separation device (2) for distillationor fractionation.

The at least one separation device (2) also preferably comprises areboiler connected to the at least one first liquid-vapor contactingdevice of the at least one separation device (2) for heating the feedstream(s) conducted to the at least one first liquid-vapor contactingdevice of the at least one separation device (2).

The at least one separation device (2) is connected directly orindirectly to the at least one second liquid-vapor contacting device (3)for conducting a distilled or fractionated liquid bottoms feed stream(5) from the at least one first liquid-vapor contacting device of theseparation device (2) to the at least one second liquid-vapor contactingdevice (3) for stripping. The at least one separation device (2) has afirst port (6) for recovering a dichlorohydrin(s)-containing distillate.

The at least one second liquid-vapor contacting device (3) is connecteddirectly or indirectly to at least one source of stripping agent (7) forintroducing one or more stripping agents into a distilled orfractionated liquid residue delivered to the second liquid-vaporcontacting device (3) via liquid residue feed stream (5), the at leastone second liquid-vapor contacting device (3) having at least one secondport (8) for recovering a dichlorohydrin(s)-containing product strippedfrom a distilled or fractionated liquid residue delivered to the secondliquid-vapor contacting device (3) via liquid residue feed stream (5).The second liquid-vapor contacting device (3) preferably has a thirdport (9) for withdrawing stripped liquid residue feed stream from thesecond liquid-vapor contacting device (3).

The third port (9) is preferably connected to the at least one reactor(1) via recycle conduit (10) for conducting a recycle feed streamcomprising a distillation- and stripper-treated fraction from the atleast one second liquid-vapor contacting device (3) to the at least onereactor (1). The recycle conduit (10) preferably has a purge (11) forremoval of heavy byproducts from the recycle feed stream.

The second liquid-vapor contacting device (3) is preferably a column andis more preferably a distillation column. The distillation column ispreferably adapted for carrying out fractional distillation under refluxconditions having a reflux zone for carrying out reflux. Strippereffluent stream (8) is preferably a distillate obtainable with such adistillation column.

The second liquid-vapor contacting device (3) preferably has a secondvent (15) for conducting a vapor phase effluent from the top of thesecond liquid-vapor contacting device (3).

The second liquid-vapor contacting device (3) is preferably a steamstripper.

To the extent that components of the above apparatus are exposed tocorrosive materials, such components are preferably fabricated ofmaterials which are resistant to corrosion by the process components.Kirk-Othmer Encyclopedia of Chemical Technology, 2^(nd) Edition (JohnWiley and Sons, 1966), volume 11, pages 323-327, presents an extensivediscussion of the corrosion resistance of metals and non-metals that canbe used in hydrochloric acid and hydrogen chloride service. Specificexamples of suitable materials are disclosed in WO 2006/020234. Specificexamples include metals such as tantalum, suitable metallic alloys(particularly nickel-molybdenum alloys such as Hastalloy C©), orglass-lined equipment.

When milder temperature conditions are used to recover DCH according tothe present invention, less expensive corrosion-resistant materials maybe used in one or more components of the apparatus downstream from thereactor(s), such as distillation or fractionation column(s) (2), thesecond liquid-vapor contacting device (3) and/or components and conduitslinking those components to each other or to other downstreamcomponents. This reduces the capital investment cost for building aproduction facility to be amortized, which reduces the overall cost ofthe process according to the present invention.

The following examples are for illustrative purposes only and are notintended to limit the scope of the present invention.

Equipment Used in the Examples

Distillation is carried out using a glass distillation column packedwith 6 mm ceramic Intalox saddles, containing two packed bed sections.Feed to the column is located between the two packed bed sections. Thecolumn is provided with a glass reboiler and two partial condensers inseries, also made of glass, for cooling the vapor stream exiting thecolumn. The first condenser is cooled with chilled glycol. A portion ofthe condensate from the first condenser is returned to the column asreflux and the rest of the condensate is collected as product.

Uncondensed vapors from the first condenser are condensed in the secondcondenser operating at a lower temperature and cooled with chilledglycol. The uncondensed vapors exiting the second condenser are passedthrough a set of cold traps before entering the vacuum pump whichprovides vacuum to the whole system. The second condensed liquid-phaseeffluent from the second condenser is collected as product.

In Example 1, the distillation residue is fed to a steam strippingcolumn. The steam stripping column has dimensions similar to those ofthe above-described distillation column.

Composition and Conditions of Feed Stream Mixture (a)

The feed stream composition and conditions shown in Table 1 below areused to provide the mixture (a) for each example:

TABLE 1 Conditions and Composition Units Feed Rate 2.5 kg/hr FeedTemperature 100 ° C. Feed Pressure 790.8 kPa Feed Composition: Hydrogenchloride 3.7 Weight-percent Water 8.4 Weight-percent1,3-dichloro-2-propanol 38.7 Weight-percent 2,3-dichloro-1-propanol 4.9Weight-percent 3-chloro-1,2-propanediol 9.1 Weight-percent2-chloro-1,3-propanediol 10.8 Weight-percent Esters 5.4 Weight-percentGlycerol 19.0 Weight-percent

As shown in Table 1, the 1,3-dichloro-2-propanol rate is 38.7weight-percent of the 2.5 kg/hr feed rate or 0.97 kg/hr and the2,3-dichloro-1-propanol rate is 4.9 weight-percent of the 2.5 kg/hr feedrate or 0.12 kg/hr. The sum of the 1,3-dichloro-2-propanol feed rate(0.97 kg/hr) and 2,3-dichloro-1-propanol feed rate (0.12 kg/hr), is 1.09kg/hr.

Example 1

In this example, a DCH recovery process is carried out according to thepresent invention using the feed composition and conditions shown inTable 1. Distillation is carried out under moderate vacuum conditionsfollowed by steam stripping.

The distillation column process conditions used in Example 1 are shownin Table 2 below:

TABLE 2 Distillation Column Process Conditions Units Condensertemperature 47.1 ° C. Condenser pressure 6.7 kPa Bottom temperature131.4 ° C. Reflux ratio (reflux rate/distillate rate) 0.36 Distillate tofeed ratio 0.50 Distillate mass vapor fraction 0.25 Pressure drop acrossthe column 1.3 kPa

Using a computer simulation based on actual data obtained in ComparativeExample 1, the distillation data shown in Table 3 are obtained.

TABLE 3 Aqueous Organic Subject Vent Overhead Overhead Bottoms UnitsRate 0.03 0.18 0.83 1.39 kg/hr HCl 68.19 29.35 2.01 — wt. % H₂O 20.5668.68 9.29 — wt. % 1,3-dichloro-2-propanol 10.85 1.87 81.65 15.85 wt. %2,3-dichloro-1-propanol 0.41 0.10 7.02 4.37 wt. %3-chloro-1,2-propanediol — — 0.01 16.31 wt. % 2-chloro-1,3-propanediol —— 0.01 19.48 wt. % glycerin — — — 34.28 wt. %

“Vent” refers to stream 14 in FIG. 1. “Aqueous Overhead” refers to theaqueous phase of a two-phase liquid-liquid decanter used to separateoverhead stream 6 of FIG. 1 after condensation. “Organic Overhead”refers to the organic phase of a two-phase liquid-liquid decanter usedto separate overhead stream 6 of FIG. 1 after condensation. “Bottoms”refers to the distillation residue stream 5 of FIG. 1. Hyphen (“-”)indicates that the weight-percent value was below 0.01.

The rate at which DCH is recovered in the overhead via distillation step(b) may be calculated as the difference between the DCH feed rate (1.09kg/hr as shown in the explanation for Table 1) and the DCH bottom rate(0.28 kg/hr) or 0.81 kg/hr.

DCH recovery is therefore 74.3 percent (0.81÷1.09×100).

The distillation residue, referred to as the “bottoms” in Table 2, isused as the feed stream for computer simulated steam stripping based onthe above described steam stripping column fed at the bottom with steamat a pressure of 1480 kPa and at a temperature of 197.7° C. at a rate of1.0 kg/hr. The simulated column pressure is kept at 13.3 kPa. Theresults obtained are shown below in Table 4.

TABLE 4 Aqueous Organic Subject Overhead Overhead Bottoms Units Rate1.15 0.07 1.17 kg/hr H₂O 81.57 17.34 4.29 wt. % 1,3-dichloro-2-propanol15.01 66.24 0.30 wt. % 2,3-dichloro-1-propanol 3.41 16.42 0.91 wt. %3-chloro-1,2-propanediol — — 19.32 wt. % 2-chloro-1,3-propanediol — —23.07 wt. % glycerin — — 40.60 wt. %

From the above data, the DCH bottom rate may be calculated by adding theweight-percent values for 1,3-dichloro-2-propanol and2,3-dichloro-1-propanol, dividing the sum by 100, and multiplying theresulting value with the 1.17 kg/hr bottom rate to obtain 0.015 kg/hr.

Table 5 shows the combined overhead recovery rate and composition fordistillation and steam stripping based on the data in Tables 3 and 4above.

TABLE 5 Total Subject Recovered in Overhead Units Rate 2.05 kg/hr H₂O49.34 wt. % 1,3-dichloro-2-propanol 45.20 wt. % 2,3-dichloro-1-propanol5.39 wt. %

DCH recovery obtained with the distillation combined with steamstripping is 98.6 percent (1.075÷1.09×100).

Comparative Example

In this comparative example, DCH recovery is determined based on theconventional high vacuum distillation process using the Example 1distillation equipment and distillation feed stream. The distillationconditions are modified to maximize DCH recovery during distillation byreducing the condenser pressure and adjusting the condenser temperatureto take the lower condenser pressure into account while maintaining thesame bottom temperature as shown below in Table 6.

TABLE 6 Distillation Column Process Conditions Units Condensertemperature 9 ° C. Condenser pressure 1.8 kPa Bottom temperature 131.4 °C. Reflux ratio (reflux rate/distillate rate) 0.37 Distillate to feedratio 0.50 Distillate mass vapor fraction 0.25 Pressure drop across thecolumn 1.3 kPa

The data obtained with the feed of Table 2 under the above distillationconditions is shown below in Table 7.

TABLE 7 Aqueous Organic Subject Vent Overhead Overhead Bottoms UnitsRate 0.03 0.24 1.08 1.15 kg/hr HCl 68.25 29.35 0.02 — wt. % H₂O 20.5768.68 3.44 — wt. % 1,3-dichloro-2-propanol 10.64 1.83 86.24 2.48 wt. %2,3-dichloro-1-propanol 0.54 0.13 10.28 1.03 wt. %3-chloro-1,2-propanediol — — 0.01 19.73 wt. % 2-chloro-1,3-propanediol —— 0.01 23.56 wt. % glycerin — — — 41.46 wt. %

The DCH overhead rate may be calculated as 1.05 kg/hr (1.09 kg/hr DCHfeed rate minus 0.04 kg/hr DCH bottom rate). DCH recovery is calculatedto be 96.3 percent (1.05 kg/hr÷1.09 kg/hr×100).

As can be seen from the foregoing, Example 1 according to the presentinvention is capable of obtaining a recovery of DCH greater than thatobtained according to the Comparative Example without imposing a highvacuum condition on the distillation column.

Advantages of the present invention include:

-   -   1. A wider selection of vacuum devices and the ability to use of        a more economical steam-jet ejector, thereby reducing capital        and operating costs;    -   2. Reduction of column size for a given feed volume due to the        ability to operate at higher pressures, further reducing capital        investment required;    -   3. Reduced heavy byproducts formation due to reduced        distillation bottoms temperatures for increased product yield        and reduced energy requirements for byproduct disposal;    -   4. Additional water introduced by steam stripping facilitates        any downstream epoxidation process by keeping the concentration        of sodium chloride formed during epoxidation below the        saturation level.

1. A process for recovering dichlorohydrin(s) from a mixture comprisingdichlorohydrin(s), one or more compounds comprising ester(s) ofchlorohydrin(s), monochlorohydrin(s), and/or multihydroxylated-aliphatichydrocarbon compound(s) and/or ester(s) thereof, and optionally one ormore substances comprising water, chlorinating agent(s), catalyst(s)s,ester(s) of catalyst(s), and/or heavy byproduct(s), wherein the processcomprises: (a) providing a mixture comprising dichlorohydrin(s), one ormore compounds comprising ester(s) of chlorohydrin(s),monochlorohydrin(s), and/or multihydroxylated-aliphatic hydrocarboncompound(s) and/or ester(s) thereof, and optionally one or moresubstances comprising water, chlorinating agent(s), catalyst(s),ester(s) of catalyst(s), and/or heavy byproduct(s); (b) distilling orfractionating the mixture of step (a) in one or more unit operations toseparate a lower boiling fraction comprising dichlorohydrin(s) and otherlower boiling components present in the mixture from the mixture of step(a) to form a higher boiling fraction comprising the residue of thedistillation or fractionation; (c) introducing a stripping agent intothe higher boiling fraction produced by step (b) for contact with thehigher boiling fraction and stripping dichlorohydrin(s) from the higherboiling fraction into the stripping agent to produce a vapor fractioncomprising dichlorohydrin(s) and stripping agent; (d) recovering atleast some of the lower boiling fraction of step (b) and the vaporfraction of step (c).
 2. The process according to claim 1 comprisingcombining the lower boiling fraction produced by step (b) with the vaporfraction produced in step (c) without prior distillation orfractionation of the vapor fraction produced in step (c).
 3. The processaccording to claim 1 or 2 wherein at least one chlorinating agent ispresent in the mixture provided in step (a).
 4. The process according toclaim 3, wherein the at least one chlorinating agent comprises hydrogenchloride.
 5. The process according to claim 3 or 4, wherein at least 50percent of the chlorinating agent(s) present in mixture (a) is removedfrom the mixture (a) prior to step (c).
 6. The process according to anyone of the preceding claims, wherein 10 to 95 percent of the totalamount of dichlorohydrin(s) in the mixture provided in step (a) isrecovered in the lower boiling fraction of step (b).
 7. The processaccording to any one of the preceding claims, wherein step (b) iscarried out at a pressure in the range from 1 kPa to 0.12 MPa.
 8. Theprocess according to any one of the preceding claims, wherein thetemperature of the higher boiling fraction during step (b) is in therange from 50° C. to 139° C.
 9. The process according to any one of thepreceding claims, wherein the stripping agent is an azeotroping agentfor dichlorohydrin(s) during step (c).
 10. The process according to anyone of the preceding claims, wherein the stripping agent comprisessteam.
 11. The process according to any one of the preceding claims,wherein at least one monochlorohydrin and/or ester thereof is present inthe mixture provided in step (a) and in the high-boiling fraction ofstep (b).
 12. The process according to any one of the preceding claims,wherein at least one multihydroxylated-aliphatic hydrocarbon compoundand/or ester thereof is present in the mixture provided in step (a) andin the high-boiling fraction of step (b).
 13. The process according toany one of the preceding claims, wherein the mixture provided in step(a) further comprises a catalyst for hydrochlorinatingmonochlorohydrin(s) and/or ester(s) thereof and/ormultihydroxylated-aliphatic hydrocarbon compound(s) and/or ester(s)thereof.
 14. The process according to claim 13, wherein the catalyst isat least one carboxylic acid, at least one ester of at least onecarboxylic acid, or a combination thereof, having a boiling point duringstep (b) greater than the boiling point of the highest boilingdichlorohydrin during step (b).
 15. The process according to claim 13 or14, wherein the catalyst (i) is a carboxylate derivative having from twoto about 20 carbon atoms and containing at least one functional groupselected from the group comprising an amine, an alcohol, a halogen, asulfhydryl, an ether, an ester, or a combination thereof, wherein thefunctional group is attached no closer to the acid function than thealpha carbon; or a precursor thereto; (ii) is less volatile than thedichlorohydrin(s); and (iii) contains heteroatom substituents.
 16. Theprocess according to any one of the preceding claims, wherein strippingagent is also introduced into the higher boiling fraction of step (b)while the same higher boiling fraction is distilled or fractionatedaccording to step (b) for contact with the higher boiling fractionundergoing distillation or fractionation and stripping dichlorohydrin(s)from the higher boiling fraction.
 17. The process according to any oneof the preceding claims, wherein the mixture provided in step (a) is inthe liquid-phase.
 18. The process according to any one of the precedingclaims, wherein the mixture of step (a) comprises water.
 19. The processaccording to claim 18, wherein step (b) comprises: (b1) vaporizing anazeotropic mixture of dichlorohydrin(s) and water from the mixture ofstep (a) to separate a lower boiling fraction comprising at leastdichlorohydrin(s) and water from the mixture of step (a) and (b2)condensing the low boiling fraction of step (b1) to form a liquidaqueous phase and a liquid organic phase comprising dichlorohydrin(s).20. The process according to claim 19, wherein additionalmulti-hydroxylated aliphatic hydrocarbon compound(s) and/or ester(s)thereof is/are introduced into condensing step (b2).
 21. The processaccording to claim 19 or 20, wherein step (b) further comprises: (b3)separating the liquid aqueous phase of step (b2) from the liquid organicphase of step (b2) and (b4) recycling at least some of the liquidaqueous phase of step (b3) to step (b1) and/or step (b2).
 22. Theprocess according to any one of claims 19 to 21, wherein condensing step(b2) comprises refluxing in a fractional distillation column.
 23. Theprocess according to any one of the preceding claims, wherein step (c)comprises distilling or fractionating the vapor fraction of step (c) forisolating dichlorohydrin(s) and stripping agent.
 24. The processaccording to any one of the preceding claims, wherein step (b) iscarried out using a packed distillation column.
 25. The processaccording to any one of the preceding claims, wherein the amount ofheavy byproducts in the high boiling fraction of step (b) does notexceed 110 percent of the amount of heavy byproducts in the mixtureprovided in step (a).
 26. The process according to any one of thepreceding claims, wherein dichlorohydrin(s) are recovered from the lowerboiling fraction of step (b) and/or the vapor fraction of step (d). 27.The process according to any one of the preceding claims, wherein thelower boiling fraction and vapor fraction recovered in step (d) aresubjected to epoxidation to form epichlorohydrin without additionalpurification of the dichlorohydrin(s) other than optionally via theliquid-liquid phase separation according to claim 21 or optionally viadistillation or fractionation according to claim
 23. 28. A method forproducing dichlorohydrin(s) comprising a process according to any one ofthe preceding claims, wherein the mixture provided in step (a) isproduced or derived from hydrochlorination of monochlorohydrin(s) and/orester(s) thereof and/or multihydroxylated-aliphatic hydrocarboncompound(s) and/or ester(s) thereof in the presence of a chlorinatingagent.
 29. The method according to claim 28, wherein thehydrochlorination step is carried out in a liquid phase at a temperaturebelow the boiling point of the lowest boiling chlorohydrin in themixture and the mixture provided in step (a) comprises at least part ofthe liquid phase effluent of the hydrochlorination step.
 30. The methodaccording to claim 28 or 29, wherein the chlorinating agent is hydrogenchloride.
 31. The method according to any one of claims 28 to 30,wherein the hydrochlorination is carried out using a source of asuperatmospheric partial pressure of hydrogen chloride as thechlorinating agent.
 32. The method according to claim 30 or 31, whereinhydrogen chloride is removed from the liquid effluent prior to step (b)via a reduction in pressure permitting escape of hydrogen chloridedissolved in the liquid effluent.
 33. The method according to claim 32,wherein at least 50 percent of the hydrogen chloride is removed from theliquid phase effluent prior to step (b).
 34. The method according to anyone of claims 28 to 33, wherein less than 1 percent DCH is removed fromthe liquid phase effluent prior to step (b).
 35. The method according toclaim 28 or 34, wherein at least some chlorinating agent is removed fromthe mixture during step (b) and recycled to the hydrochlorination step.36. The method according to any one of claims 28 to 35, wherein thehydrochlorination is carried out in the presence of catalyst(s) forhydrochlorinating the monochlorohydrin(s) and/or ester(s) thereof and/ormultihydroxylated-aliphatic hydrocarbon compound(s) and/or ester(s)thereof and catalyst(s) is/are present in the mixture (a).
 37. Themethod according to any one of claims 28 to 36, wherein all of the stepsof the method are carried out simultaneously with each other and themethod is carried out continuously for a time period of at least onehour.
 38. The method according to any one of claims 28 to 37, wherein atleast some of the higher boiling fraction treated in step (c) isrecycled to the hydrochlorination step.
 39. The method according toclaim 38, wherein at least 95 percent of the dichlorohydrin(s) producedduring hydrochlorination is recovered in step (d).
 40. An apparatussuitable for producing dichlorohydrin(s) frommultihydroxylated-aliphatic hydrocarbon compound(s) and/or ester(s)thereof comprising: (1) at least one reactor; (2) at least oneseparation device comprising at least one first liquid-vapor contactingdevice having a bottom end and a top end for applying a graduallydecreasing temperature gradient from the bottom end to the top end tosubstances within the first liquid-vapor contacting device; and (3) atleast one second liquid-vapor contacting device for contacting a liquidwith a vapor-phase stripping agent, wherein the at least one reactor (1)is connected directly or indirectly to the at least one separationdevice (2) for conducting a reactor effluent feed stream (4) from the atleast one reactor (1) to the at least one first liquid-vapor contactingdevice of the at least one separation device (2) for distillation and/orfractionation, the at least one separation device (2) is connecteddirectly or indirectly to the at least one second liquid-vaporcontacting device (3) for conducting a distilled or fractionated liquidresidue feed stream (5) from the at least one first liquid-vaporcontacting device of the at least one separation device (2) to the atleast one second liquid-vapor contacting device (3) for stripping, theat least one separation device (2) having a first port (6) forrecovering a dichlorohydrin(s)-containing distillate, and the at leastone second liquid-vapor contacting device (3) is connected directly orindirectly to at least one source of stripping agent (7) for introducingone or more stripping agents into a distilled or fractionated liquidresidue delivered to the second liquid-vapor contacting device (3) vialiquid residue feed stream (5), the at least one second liquid-vaporcontacting device (3) having at least one second port (8) for recoveringa dichlorohydrin(s)-containing product stripped from a distilled orfractionated liquid residue delivered to the second liquid-vaporcontacting device (3) via liquid residue feed stream (5).
 41. Theapparatus according to claim 40, wherein the connection for conducting areactor effluent feed stream (4) from the at least one reactor (1) isadapted to conduct a liquid-phase feed stream from the at least onereactor (1).
 42. The apparatus according to claim 40 or 41, wherein theat least one separation device (2) comprises at least one flash vesseland the at least one reactor (1) is connected to at least one firstliquid-vapor contacting device of the at least one separation device (2)via the at least one flash vessel, whereby the feed stream conductedfrom the reactor (1) is separated into a vapor phase and a liquid phasein the flash vessel by reducing the pressure on the liquid phase and theseparated liquid phase is introduced into the first liquid-vapor phasecontacting device of separation device (2) for distillation orfractionation.
 43. The apparatus according to any one of claims 40 to42, wherein the at least one second liquid-vapor contacting device (3)is connected to the at least one reactor (1) via recycle conduit (10)for conducting a recycle feed stream comprising a distillation- andstripper-treated fraction from the at least one second liquid-vaporcontacting device (3) to the at least one reactor (1).
 44. The apparatusaccording to claim 43 further comprising a purge (11) in the recycleconduit for removing heavy byproducts.
 45. The apparatus according toany one of claims 40 to 44 further comprising a means for applying avacuum to the at least one first contacting device of the at least oneseparation device (2) for reducing the pressure in the at least onefirst liquid-vapor contacting device of the at least one separationdevice (2) below ambient atmospheric pressure.
 46. The apparatusaccording to claim 45, wherein the means is a steam-jet ejector.
 47. Theapparatus according to any one of claims 40 to 46, wherein the top endof the at least one first liquid-vapor contacting device of the at leastone separation device (2) has a vent (14) for removing gases at the topof the at least one first liquid-vapor contacting device of the at leastone separation device (2).
 48. The apparatus according to any one ofclaims 40 to 47, wherein the at least one first vapor-liquid contactingdevice of the at least one separation device (2) is a packeddistillation column.
 49. The apparatus according to any one of claims 40to 48, wherein the second vapor-liquid contacting device (3) comprises acolumn and the at least one column of the at least one separation device(2) and/or the second vapor-liquid contacting device (3) is/are adistillation column adapted for carrying out fractional distillationunder reflux conditions having a reflux zone for carrying out reflux.50. The apparatus according to claim 49, wherein a liquid-liquid phaseseparator is connected, directly or via a cooling device, to the refluxzone of the distillation column(s) for separating a condensed liquidaqueous phase from a condensed liquid organic phase and for conductingthe liquid aqueous phase from the liquid-liquid phase separator to thereflux zone of the distillation column(s).
 51. The apparatus accordingto any one of claims 40 to 50, wherein the apparatus further comprisesone or more distillation columns, extraction columns, absorptioncolumns, reboilers, and condensers, and combinations thereof, connectedwith the at least one reactor (1) and/or the at least one column (2).52. The apparatus according to any one of claims 40 to 51, wherein theat least one separation device (2) comprises a reboiler connected to theat least one first liquid-vapor contacting device of the at least oneseparation device (2) for heating the feed stream(s) conducted to the atleast one first liquid-vapor contacting device of the at least oneseparation device (2).
 53. The apparatus according to any one of claims40 to 52, wherein the at least one reactor (1) comprises a plug flowreactor.
 54. The apparatus according to any one of claims 40 to 53,wherein the second vapor-liquid contacting device (3) is a steamstripper.